But the Lords don't have to answer to voters. And before signing off on Brexit, they wanted a commitment from the government.

Baroness Julie Smith quoted another Lord's remarks from a previous session to emphasize that "any European citizen living in Britain has a right to remain here, and that right will not be in any way affected by Brexit."

The chamber voted 358-256 to amend the Brexit bill with a requirement that any exit deal out of the U.K. includes a specific provision to protect the country's EU expats.

The Commons is likely to reject those changes, which means the bill goes back to the Lords, and then back to the Commons, and so on until the two chambers can agree on the final language.

And all the while, the clock is ticking on Prime Minister Theresa May's pledge to start the Brexit process by the end of this month.